Changeable pitch propeller unit



May5,1942. H. K. MQOE 2,282,077

CHANGEABLE PITCH PROPELLER UNIT Filed Feb. 5, 1940 the invention and wherein antforms ol odsetf' Pienter May s, 1942 UNrTEp STATES PATE asseoir NT oFFicE Claims.

This invention relates to airplane propellers of the changeable pitch type, and one important object is to provide a changeable pitch propeller wherein the pivotal axes of the propeller blades are extended along or forwardly of the leading edges of the blades, thereby facilitating the au.- tomatic turning of the blades responsively to the speed of the motor and preventing or lessening vibration in the blades.

By this odset mounting of Ra P. M. of the motor are pull of the propeller, the air against the the blades, as the reduced, due to the pressure is increased I delivery side of the propeller. In other words the air pressure the motor is pulling against has a leverage on the olf-set blades to automatically turn them to corresponding pitch position.

Another object is to provide a changeable pitch propeller adapted ior use upon a twin motored or multiple motored plane, wherein the propeller blades rotation on their axes, that the blades will automatically feather against the wind, incase one motor dies, thereby reducing air resistance.

Another object is to provide a changeable pitch propeller the blades of which are set under spring tensionwith an independent motor control governing the spring tension and ltherefore the pitchY of the blades..

Still another object is to provide an airplane propeller having rotatably journaled blades designed to automatically set themselves at a pitch best adapted to the speed of the motor, the airstream and the load carried, the blades being linked however to spring or resilient tension elements, and these elements being in turn motor controlled to increase or diminish the tension on the springs or tension elements, to change the pitch or the blades contrary to the normal automatic action of the blades in' flighte With the stated objects in view together with such other advantages as may appear from the specification, certain preferred embodiments of the invention and the several structural features thereof are shown in the drawing. wherein:

Figure l is a plan view of the elements of one form of the invention as assembled, including the outer end of the propeller drive shaft and the in-l ner ends or shanlrs of the propeller blades in sec-7 tion.

Figure 2 is a plan view of a modied form ol ce :fm elements shown in Figure i are omitted or modified.

Figures 3, 4 and 5 are plan views of three varipropeller blades.

are so designed and freely mounted for `plate l and whereby the (Ci. 17o-160) In practising this invention, and as illustrated in Figures 1 and 2, the engine drive shaft 5 has rigidly secured at the forward end thereof a cylindrical housing 6 which is formed with a central socket or sleeve 6a for engaging the threaded forward end of the shaft. 'llhis end of the shaft is passed snugly through the sleeve and a heavy nut l is turned onto the threaded end of the shaft, and laterally overlaps thev margins, thereby firmly locking the housing d to the shaft El. An integrally formed ring 6b extended from the housing 8 encircles the nut l inside the house ing, and a beveled gear 8 having a hub sa is rotatably journaled by said hub upon the ring tb ci the housing, the ring 8b of beveled gear teeth being disposed adjacent the cylindrical rim of the housing. A number of adjustment screws il are passed-threadedly through the rear side of the housing adjacent the gear E, the inner ends of these screws having a bearing against the gear latter may be pressed inwardly of the' housing, for a purpose later pointed out.

A pair of diametrically aligned hub holes 6c are formed through the cylindrical rim of the housing Cl. and a pair of diametrically aligned metallic hub sleeves I i are rigidly seated through these hub-holes andprotruded radially outward,

A pair of at propeller blades il are rotatably and slidably journaled by their rounded metallic Shanks l2a through said sleeves. The sleeves il are formed with arcuate and rearwardly turned cam slots lla adapted to slidably engage adjustment or blade turning pins or studs 82h seated in the Shanks |2a, the purpose of which arrangement will be later pointed out. The inner ends of the Shanks lia are reduced and threaded to provide threaded spindles Zc for engaging bored and tapped nuts il designed to function as pitch 0 regulators for the blades l2. The nuts or regubut beingr rotatable lators I3 are formed withA laterally extended Aspring seats i3a and with shaft bores lsb centrally through their closed ends, the walls of said bores being grooved or fluted as at @de in regular spaced relation. i

Borea klare extended axially into the ends of the spindles 2a in exact alignment with the IIb ofthe regulator nuts it, said bores I4 being suiliciently greater in diameter than the .bores of the nuts i3 to rotatably and slidably engage splined stub shafts la passed slidably through the fluted bores 63h of the nuts Il, the splines lia of the shafts engaging the flutes lic so as to rotate thenuts with the shafts, within the larger bores it of the spindles. A pair of shaft supporting webs or brackets I6 are rigidly anchored at i1 centrally to the inner face of the frontal side of the housing 6, in spaced relation and with their inner webs Ita extended in spaced and parallel relation. The inner webs Ia are formed with shaft bores- IBc aligned and dimensioned with the bores I3b of the nuts Il. The innerl ends of the shafts I5 are journaled through the bores iBcl of the brackets I6, the splines I5a being stripped at the journals, and bevel gears I'l are rigidly anchored at I8 on the inner ends of the shafts I5, inwardly of the brackets I6.

A reversible electric motor I5 is bolted at 20 centrally to the outer face of the frontal side of the housing 8, with its extended shaft 2I jour naled at 22 through this side of the housing, and a small pinion bevel gear 23 is rigidly keyed to the inner end of the shaft and placed in mesh with the gears I1 at each side.

Bevel gear rings 30 are slidably splined at 3i to the shanks I2'a inside the cylindrical rim of the housing 6. Bevel teeth 30a are carried by these rings, the same being meshed with the mating teeth 8b of the gear 8. Bali thrust bearings 32 are journaled on the shanks I2a between the inside of the cylindrical rim of the housing 6 and the bevel gear rings 30.

The shanks I2a are grooved or fluted longitudinally` as at I2d and teeth 30h are formed around the inner margins of the rings 30 and slidably engage the grooves' I2d of the shanks. Coil springs 34 encircle the Shanks Ila and are braced at their ends between the seats I3a of the regulator nuts I3 and the outer ring Bil.

An important feature of the invention lies in the manner of mounting the propeller blades I2, in that the axes indicated at I2e, on which the blades turn or rotate, extend through the leading edges I2! of the blades, as shown in Figures 3, 4, 5. It is thought that this feature is novel, and by'virtue thereof the blades will 'automatically turn and feather" against the wind in case a motor should fail or go dead,

thus reducing resistance and enabling the other! motors to function more efficiently. By this design and mounting of the propeller blades, the harder the air pressure against them, tending to slow the motor down, the more the blades turn edgewise in cutting the air-stream', to-a lower pitch angle, thus allowing the motor to hold a constant speed. This offset or leading edge method of mounting the blades also prevents or reduces danger of vibration in the blades.

The blade control motor I9 is wired for the t control of the pilot by wires 40 extended from the motor to rings II on the sleeve 6a, the rings slidably contacting brushes (not shown) on the motor housing and from which are extended wires to control switch (not shown) of the pilot. In the operation of the' assembly .as` shown and described and with the drive shaft 5 and motor I9 inert, the springs ll being braced between the gear ring 30 and the spring seats lla of the' nuts I3, will urge these elements-asunder, pressing the gear ring 3l against or onto the thrust bearing 32, and pressing the nuts I3 inwardly. The nuts Il being in rotatable threaded engagement with the spindles .I2c of the propeller blades I2, 'these blades will be drawn inwardly to their limit, the blade studs l2b will move to the innerends of the cam slots Ila of the sleeves Il, and the flat blades I2 will be turned edgewise towards or into a com'- asseoir through them edgewise, the blades being now in their idle or starting position. As the shaft 5 is energized and the blades I2 begin to rotate, centrifugal force will urge them outwardly with the shanks I2a sliding slightly through the sleeves II. In turn the blade studs IIb will travel outwardly through the arcuate cam slots IIa, this action resulting in partially rotating the blades I2 outwardly from a common plane and impinging the air at a more oblique angle, thus drawing the airplane (not shown) forwardly. As the shaft 5 picks up speed from the source of power (not shown), the studs |212 move vfurther outwardly through the slots IIa, turning the blades out more sharply, and this action continues until an equilibrium is established between the speedA of the propeller blades, the resistance offered by the air and the load carried.

However if it is found desirable by the pilot in any situation to disturb such automatic equilibrium, and to increase or decrease the pitch of the blades irrespective of their normal pitch at any given speed of rotation, this may be done by energizing the electric motor I5. Such action rotates the gears I1, the splined shafts I5 and the regulator nuts I3. The latter then turn either further onto the threaded spindles I2c, or the reverse, according to the direction of rotation of the motor shaft 2i. If the nuts I3 are turned further onto the spindles the propeller blades are drawn inwardly under the increased mon plane passing `pressure of the springs Il, and the Iblades are consequently turned more edgewise to the air, or more towards a common plane. The reverse rotation of the motor shaft and nuts pushes the blades outwardly and turns them more obliquely to the air stream, both movements being due to the stated outward and rearward movements of the studs I2b throughthe slots IIa. Should the source of power of the airplane fail,

the blades I2 will under the wind pressure, autoleading edges, may be applied to any conventional form of changeable pitch propellers.

The description given of the operation of the device, is as applied toa propeller rotating clockwise as viewed from the pilots seat, with the .propeller blades turning downward and rearward for increasing their pitch against the air stream.

If desired, the independent motor control for altering the normal blade pitch, may of course be omitted, and the device limited to the normal automatic elements described and as illustrated in Figure 2. The nuts Il could then be adjusted and locked by hand to place the springs Il under the desired tension.

In this assembly is shown a spider and gear unit I5, anchored medially to the frontal wall of the housing l, and arranged to turn the blades in unison. AThis unit includes a pair of bevel gears mounted in opposed spaced relationion splined stub shafts passedV slldably into be forced inwardly by the tubular and interiorly iluted blade spindles I 2a, and bevel pinion gears 48 mounted and journaled on a shaft extended through the spider as shown,

and placed in mesh with the gears 46. The bevel to the forward end of the shaft, and including= propeller blades with shanks oppositely, radially, rotatably and slidably journaled through the cylindrical rim of the housing, the inner ends of 2. In a device as defined in claim 1, means for automatically varying the pitch of the propeller blades as they move outwardly or inwardly.

3.' In an airplane changeable pitch type, and including a drive shaft having a vcylindrical Housing axially anchored at its forward end, and including propeller blades with Shanks oppositely, radially, rotatably and slidably journaled, laterally through the cylindrical rim of. the housing, coil springs embracing the blade-Shanks and braced at their ends between settings to normally press the blades inwardly, means for increasing the pitch of the blades as they are projected outwardly by centrifugal force under rotation of the housing, an electric motor on an outer end of the housing the shaft thereof being extended the shanksbeing screw-threaded and axially bored, blade regulator nuts on the inner threaded ends of the Shanks, said nuts being formed with laterally disposed spring seats and .with

' shaft bores centrally through their ends; the

walls of said bores being uted axially, splined stub-shafts passed yslidably through the uted bores of'the nuts and rotatably and slidably into the aligned bored ends of the blade Shanks, an-

nular ball-bearing units freely embracing the blade Shanks linside the rim of the housing, coil springs embracing the inner ends of the blade shanks and braced between the spring seats of the regulator nuts and the outer ball 5;

bearing units for normally urging the propeller blades inwardly, an electric motor anchored centrally at the front of the housing with its extended shaft journaled therethrough, electrical leads and connections extended from the motor to the I control of the pilot, and gear connections between the motor -shaft and the said regulator nuts of the blade shanks, whereby the nuts and the slidably associated splined stub-shafts may be rotated for compressing or releasing the springs of the blade shanks to positively urge the propeller blades inwardly as against 'centrifugal force or permit them to move outwardly under such lforce.

and journaled centrally into the housing, controls for the motor, and means connecting the motor shaft with the spring-settings of the blade Shanks for varying the tension of those springsettings through the operation of the motor, portions of said spring-settings being movable for such purpose. 4. In a device of thekind described and including a housing with a pair of propeller blades having their Shanks diametrically oppositely, rotatably and slidably journaled through the opposite walls of the housing, means for partially rotating the shafts in unisonfor changing they pitch of the blades, the peripheries of the shank ends being screw-threaded, complementally threaded press elements on the threaded Shanks, coil springs embracing the shanks and braced between the walls of the housing and said press elements, an electric motor on the housing having its shaft journaled thereinto, controls for the motor, and connections between the niotor shaft and the threaded press elements on the shanks for rotating the press elements in unison for retracting the blades against centrifugal force, or the reverse.

5. In a device according to claim 4, means for automatically varying the pitch of the propeller blades as they move outwardly or inwardly.

HAMILTON K. MOORE.

propeller assembly of the 

